Preparation and some properties of hydrophilic membranes obtained by radiation grafting of methacrylic acid onto fluorinated polymers

Hydrophilic membranes were prepared by direct radiation grafting of methacrylic acid (MAA) onto poly(tetrafluoroethylene‐perfluorovinylether) copolymer (PFA) and poly(tetrafluoroethylene‐hexafluoropropylene) copolymer (FEP) films followed by alkaline treatment to confer ionic character in the graft copolymer. Addition of 0.5 wt % FeCl3 to the monomer solution effectively inhibited the homopolymerization process and higher grafting yield was obtained. The graft copolymerization of MAA was carried out in presence of methanol/water mixture (30/70 wt %) in nitrogen atmosphere irradiation. The dependence of the grafting rate on MAA concentration was found to be 0.63 and 0.94 order for PFA and FEP films, respectively. This grafting system proceeds by the front mechanism in which the monomer diffuses through the already grafted layer formed initially. Some selected properties of the graft copolymers were investigated. It was found that the grafted membranes possess good mechanical, electrical, and hydrophilic properties which may make them promising in some practical applications.